The way people have booked their travel plans has evolved over time. Initially, travel bookings were done by travel agents. Then, online bookings became popular through various web sites, which offer reviews as well as links for booking hotels, purchasing airline tickets, etc.
Also, people have changed the way they travel and what they do when they travel. For example, it is not uncommon for travelers to prefer to rent people's homes rather than stay in hotels. Also, travelers often share their travel experiences with friends through social media. Also, many travelers may prefer site seeing on their own instead of with a guide. Even with the availability of travel web sites, it is still time consuming and laborious to book travel plans, especially given the variation and ever changing travel habits of individuals.